The present invention relates to improvements in a green-compact electrode for discharge surface treatment with which a discharging operation is performed in working fluid to form a hard coating film on the surface of an object which must be processed, a manufacturing method therefor, a method and an apparatus for performing discharge surface treatment and a method of recycling green-compact electrode for discharge surface treatment.
A conventional technique for performing discharge surface treatment has been disclosed in Japanese Patent Laid-Open No. 9-192937. According to the foregoing disclosure, a material for producing a hard carbide, such as Ti, is employed to serve as an electrode. Then, discharge is caused to occur with a metal material, which is a material to be machined, so that a strong hard coating film is formed on the surface of the metal which is a material to be machined.
FIG. 5 shows a method of molding a green-compact electrode obtained by compression-molding metal powder or the like and arranged to serve as the electrode for use in the discharge surface treatment process. Referring to FIG. 5, reference numeral 51 represents a punch, 52 represents a die and 53 represents a green-compact electrode in the form of powder. The powder green-compact electrode is compression-molded by using a mold.
When the green-compact electrode shown in FIG. 5 is molded, great pressure is generated on the side surfaces of the die 52. Therefore, mold release characteristics required after the molding process are unsatisfactory. Thus, there arises a problem in that the green-compact electrode obtained by compression molding is easily broken. Another problem arises in that the green-compact electrode is too brittle. Therefore, the manufacturing yield of the green-compact electrode excessively deteriorates.
When the brittle green-compact electrode is employed in a discharge surface treatment, the hard coating film formed on the object, which has been subjected to the discharge surface treatment, cannot be uniform.
To overcome the above-mentioned problems, a mold release agent or a hardener is required. When oleic acid or the like is employed which is usually employed as a mold release agent for a sintered body, the mold release agent disperses and melts in the working fluid. Therefore, components in the working fluid are changed. Therefore, a coating film having a required quality and hardness cannot be formed on the surface of the object which must be machined. Also, the use of usual hardeners causes similar problems.
To overcome the above-mentioned problems, a first object of the present invention is to improve the brittleness of a green-compact electrode for discharge surface treatment so as to form a stable and uniform hard coating film on an object which must be machined by performing discharge surface treatment using the green-compact electrode for the discharge surface treatment.
A second object of the present invention is to improve the mold release characteristics and hardenability of a green-compact electrode for discharge surface treatment required to perform compression molding so as to efficiently manufacture the green-compact electrode for discharge surface treatment.
A third object of the present invention is to obtain a method and apparatus for performing discharge surface treatment which do not exert an influence on the formation of a hard coating film on an object, which must be machined, even if the discharge surface treatment is repeated and enabling the characteristics for forming a uniform coating film of the material of the electrode to be exhibited.
A fourth object of the present invention is to obtain a method of recycling a green-compact electrode for discharge surface treatment.
A green-compact electrode for discharge surface treatment disclosed in a first aspect of the present invention is obtained by mixing a material of the green-compact electrode for discharge surface treatment and fluid which is the same as the working fluid.
A green-compact electrode for discharge surface treatment disclosed in a second aspect of the present invention has a structure that a mixture ratio of the fluid which is the same as the working fluid with respect to the green-compact electrode for discharge surface treatment is 5 wt % to 10 wt %.
A method of manufacturing a green-compact electrode for discharge surface treatment disclosed in a third aspect of the present invention comprises the step of: compression-molding a mixed material of a material of a green-compact electrode for discharge surface treatment and fluid which is the same as working fluid to manufacture a green-compact electrode for discharge surface treatment.
A method of manufacturing a green-compact electrode for discharge surface treatment disclosed in a fourth aspect of the present invention comprises the step of: compression-molding a mixed material having a structure that a mixture ratio of the fluid which is the same as the working fluid with respect to the green-compact electrode for discharge surface treatment is 5 wt % to 10 wt % to manufacture a green-compact electrode for discharge surface treatment.
A method of performing discharge surface treatment disclosed in a fifth aspect of the present invention comprises the step of: using a mixed material of a material of the green-compact electrode for discharge surface treatment and fluid which is the same as the working fluid as an electrode.
An apparatus for performing discharge surface treatment disclosed in a sixth aspect of the present invention comprises: a material of the green-compact electrode for discharge surface treatment and fluid which is the same as the working fluid which constitute the green-compact electrode for discharge surface treatment.
A method of recycling a green-compact electrode for discharge surface treatment disclosed in a seventh aspect of the present invention comprises: a compression molding step for molding mixed material of a material of the green-compact electrode for discharge surface treatment and fluid which is the same as the working fluid; a discharge surface treatment step for performing a discharge surface treatment process by using an electrode obtained by compression molding; and a pulverizing step for forming portions in which the electrodes are left after the discharge surface treatment step has been completed into powder, wherein the compression molding step and following steps are repeated after the pulverizing step has been completed.